1. Field
Aspects in accordance with the present invention relate to a method for preparing data for hybrid exposure used in lithographic process using both electron beam exposure and reticle exposure in a process for manufacturing a semiconductor integrated circuit.
2. Description of Related Art
Electron beam exposure (hereafter referred to as “EB exposure”) can perform high-accuracy exposure and can eliminate costs for reticle preparation because no reticle is required. However, since a large amount of time is required for exposure treatment, the throughput of lithographic processing is lowered.
Therefore, hybrid exposure has been used, wherein exposure for patterns having large areas that do not require exposure accuracy (for example, dummy patterns) is performed by reticle exposure, and exposure for fine patterns that requires exposure accuracy is performed by EB exposure. Hybrid exposure improves the throughput on the exposure process, and also solves the problems caused during the EB exposure of patterns having large areas, such as out-of-focus beams.
However, due to the miniaturization of circuit patterns in semiconductor integrated circuit devices, high-accuracy reticle exposure has also been required. Specifically, a correcting treatment, such as an OPC treatment, which is an optical treatment for improving accuracy, wherein an ArF light source that enables high-accuracy exposure by light having a short wavelength is used as the light source for reticle exposure; a LFC treatment, which is a lens correcting treatment for improving accuracy; and a phase shifter treatment for correcting reduced accuracy caused by local flare, must be performed. Therefore, costs for reticle manufacturing have been significantly raised, and the advantage of performing hybrid exposure has been reduced.
The adoption of reticle using a KrF light source that outputs light having a long wavelength can save costs in reticle manufacturing. The reticle using a KrF light source does not require the above-described correcting treatment, such as an OPC treatment, a LFC treatment, and a phase shifter treatment, thus reducing reticle preparation man-power and costs for reticle manufacturing.
However, the reticle using a KrF light source cannot expose fine patterns with high accuracy, and cannot deal with fine exposure patterns, in recent years.
In Japanese Patent Laid-Open Nos. 2001-330940, 2001-109128, and 2001-189259, configurations for taking out reticle patterns using the resolution dimension of KrF exposure, or the resolution dimension of deep-UV as the reference. However, since reticle patterns are taken out by the above-described image processing, the time required for processing cannot be shortened.
Although Japanese Patent Laid-Open No. 3-54817 discloses a method for preparing patterns for performing hybrid exposure, means for solving the above-described problems have not yet been disclosed.
Although Japanese Patent Laid-Open No. 4-26109 discloses a method for preparing an image pattern for performing hybrid exposure, since the pattern is prepared by image processing accompanying change in parameter values or image processing procedures, the above-described problems have not yet been solved.
Although hybrid exposure by reticle exposure using KrF exposure and EB exposure requires no correcting treatment when reticle data is prepared by ArF exposure, it still has a problem wherein violation site detecting treatment to determine whether the design rule is satisfied or not and treatment to correct the violation site take a long time.